While the Act Solar Active Power Management Whitepaper describes the problems PowerString (datasheet, product overview) solves, it does not delve into the technology. As I understand it, PowerString senses the main solar array MPP (Maximum Power Point) voltage and monitors the string current to determine whether the string solar modules are generating maximum power. If any string solar modules are impaired or shaded, PowerString uses a Buck Converter arrangement to bias the unimpaired or unshaded modules at their MPP voltage thus recovering secondary and tertiary string power losses. The PowerString bucks the array MPP voltage to match the lower MPP voltage of the power generating modules.

Now with Act Solar we can further improve the performance and efficiency of solar systems, at the same time providing monitoring capabilities not available before. This will make solar installations more efficient and ultimately reduces the cost of solar energy for everyone.

Act Solar’s wireless status reporting, diagnostics, and remote Solar Operations Center (SOC) directed towards large scale PV deployments were further icing for the acquisition by National and may have trumped National’s residential focused efforts.

Act Solar has imitators and competitors even if the technology details are different. For example, SatCon Technology Corporation (NASDAQ:SATC) offers the Solstice Subcombiner for String-Level MPPT, DC-to-DC Conversion, and Communications. SolarEdge is developing a holistic, distributed DC solution with an MPPT (MPP Tracking) circuit per solar module and power line communication mating to a simplified, central DC to AC inverter.

When I first pondered how National’s SolarMagic might function, my linear analog skills were fixated on a Boost approach that would step-up the shaded module voltage to the module’s nominal Maximum Power Point voltage. Given the per module architecture, this remains a plausible explanation. The National Semiconductor SolarMagic technology announcement last summer was:

We realized SolarMagic making the most of our analog semiconductor technology. It is in the form of a module, not a standalone IC. The module houses intelligent analog ICs and other technical components. This module is connected with each solar cell module (including multiple solar cells) when used. Accordingly, a system combining three solar cell modules in series and two in parallel requires six SolarMagic modules.

The SolarMagic module is controlled to always operate at MPP in each solar cell module. However, I can’t reveal details of the control technology at the moment. I suppose I can tell them in the first quarter (January to March) of 2009, in which SolarMagic’s volume production and shipments are slated to start.

SolarMagic. This is the first-generation model. Its price is about US$150. “If the production volume increases, the price will naturally drop as a result,” Halla said.

Halla holds the highest hope for SolarMagic among the five products. SolarMagic executes MPP (maximum power point) control in each solar cell to prevent energy output from decreasing when a solar cell module is partially shaded, he said.

Although the unrealistic $150 SolarMagic price per module stated by National Semiconductor CEO Brian Halla might be product life cycle value based or just a list price, I think the photovoltaic market is smart enough to drive this fantasy towards cost plus pricing. Or is a cost reduction to a string based solution already required? Perhaps PowerString will become SolarMagic by another name? There may be a simple answer to all these questions. A chip company just does not have the corporate DNA to market and sell a system solution.